The act of the tissue in taking up the laser energy, causing a reaction within the tissue.

Absorption peaks of oxyhemoglobin

Places on an absorption curve where light absorption is strong

Aiming beam

Usually a second low power laser which provides a defined target area. Used with infrared or other invisible wavelengths

Anatomical parts of hair

Follicle, bulb, bulge, vascular, supply (matrix) and hair shaft

Angioma (Cherry, spider)

a.k.a. Capillary hemangioma's. Tumor composed of a mass of tiny blood vessels, bright red in color, usually 2-5mm in size, and are flat or raised

ANSI

American National Standards Institute - voluntary nationally recognized group establishing standards for equipment use

Articulated arm

A laser delivery system that utilizes a jointed arm, and mirrors

Atrophic

A wasting, progressive degeneration and loss of function of any part of the body

Becker's nevus

Similar to Café-au-lait macules, but more rare, and typically larger (5-40cm) Also have course hair present within the patch, and usually located in the shoulder area

Café-au-lait

Light tan to light brown macules often apparent at birth, epidermal in depth, and can be from 1cm-20cm in diameter

Cavitation

Formation of a cavity or erosion

Chloasma/Melasma

Melasma - light to medium brown discoloration of the face commonly associated with pregnancy called "mask of pregnancy"

Chromophore

A target that absorbs light

Class of lasers defined

Broad classification of lasers based on the ability to cause injury, Class I-IV, Class IV being the most dangerous/powerful

Coherent

All the waves of the laser beam are lined up in phase with each other in time and space

Collimated

All the waves of the laser beam are parallel to each other and don't converge or diverge very much

Congenital nevi

Nevi which are present at birth

Congenital vascular malformation

General term for vascular lesion present at birth, such as Port Wine Stain, hemangioma's and venous malformations

Corneal Shields

Protective covering which is placed directly onto the surface of the eye

Collimated

All the waves of the laser beam are parallel to each other and don't converge or diverge very much

DCD

Dynamic Cooling Device - sprays a cryogen or cooling agent on the skin prior to the laser pulse being fired

Delivery system

Method to apply laser energy to a patient, i.e.. Articulating arm, fiber, handpiece

Dermatitis

Inflammation of the skin

Distance gauge

The act of the tissue in taking up the laser energy, causing a reaction within the tissue.

Ectatic

Dilatation of a hollow organ or tubular structure

Edema

Swelling due to collection of fluid in interstital space

EMLA

Topical anesthetic cream -2.5% lidocaine and 2.5% prilocaine

Energy density

How much energy is contained within a given spot size - see joules

Epidermis

The outermost thin layer of skin

Epilation

The removal of hair and its roots

Erythema

Redness of the skin

Fiber

A quartz of glass filament used as a delivery system for laser energy

Fitzpatrick skin types

Classification system of skin types based on tanning and melanin content (Types 1-6). Type 1 being fair skin, easily burned - to type 6 never burn very dark skin

Flashlamp excited

Utilizing high intensity flashlamps to excite a lasing medium to produce laser energy

Focal length

Distance between the lens and the focal point, or the distance from the lens which provides the proper beam size

Focusing lens

Lens used to focus the laser beam to a specific spot size

Gating or shuttered pulse

Method of using a mechanical shutter to produce a "pulsed" effect in a laser beam

Hair cycle (anagen, catagen, telogen)

The growth phases of hair

Hemangioma

Benign tumor made up of blood vessels

Hirsuitism

Excessive hair on cheek, chin, lip or chest; especially in women

Hyperpigmentation

Decreased coloration of the pigmentation in a tissue or part

Incoherent

White light, many wavelengths present, i.e., does not have the properties of a laser

Inflammation/inflammatory response

Tissue reaction irritation, infection, or injury marked by localized heat, swelling, redness, and pain

Intraoperative

Meaning "during" the surgical procedure

Joules (/cm2)

A measurement of energy density within a given spot size

Keloids

A nodular mass of scar tissue which has grown well outside the original boundaries of a scar

Laser

Light Amplification by Stimulated Emission of Radiation

Laser parameters

Characteristics of a laser beam, or the settings used on the laser device, can include: wavelength, spot size, energy (joules), repetition or firing rate

Lentigines

Small tan to brown epidermal lesions or macules usually arising from sun exposure and increase in number as a person ages

Medium (liquid, solid, gas)

Substance which produces the laser energy

Melanin

The pigment which is produced by melanocytes in the skin

Melanocytes

The pigment producing cells in the skin

Melanocytic nevi

Medium to dark brown maciles which are dermal in depth and tend to occur on the truck and extremities. Can be from .5cm to several centimeters in diameter, and have a relative higher risk of becoming malignant

Melanosomes

Melanin containing organs within the melanocytes

Microseconds

10-6 seconds, or .00001 seconds

Milliseconds

10-4, or 1/1000th of a second

Monochromatic

Meaning one color

Monte Carlo Simulation

Computer optical simulation of photons moving through tissue based on optical properties

Nanometer

10-9 meters, or .000000001 meters

Nanoseconds

10-9 seconds, or .000000001 seconds

Nevus of ota

Blue gray lesion on the face most commonly seen in Asian populations. Dermal in depth, and usually seen around the eye, temple and cheek area.

Non-ionizing/ionizing radiation

Non-ionizing forms of radiation include: light, heat, radio waves. Ionizing forms include: x-rays, gamma rays. Ionzing radiation can cause cell mutation or death

Optical density

How dense or resistive a substance is to light energy

OSHA

Occupational Safety and Health Administration

Perifollicular edema

Swelling due to collection of fluid in the interstital space (area around the depression in the skin from which the hair emerges). Positive sign of proper energy delivered for hair removal

Photo-acoustic

light that generates a acoustic shock wave effect in tissue

Photo-ablation

The act of removing tissue by vaporization with light

Photo-chemical

Act of light causing or initiating a chemical reactioned

Photons/molecules of light

Light energy given off by an excited atom

Photosensitivity

Something that causes (drug) increased sensitivity to light

Pokiloderma of civatte

Chronic discoloration of the side of the neck and upper chest associated with chronic sun exposure. Can include pigmentation and telangiectasia's

Port Wine Stain (PWS)

An enlarged red-blue capillary hemangioma that resembles a map, is non-palpable, and covers large area of the face and the upper trunk. Also called nevus, nevus flammeus

Post-inflammatory pigmentation

Area(s) of darkening or increased pigment in a laser treated area after treatment

Postoperative

Pertaining to after a surgical procedure

Preoperative

Pertaining to prior to surgical procedures

Protons, neutrons, electrons

Basic components or building blocks of atoms

Pruritis

Itching

Pulse duration/length

The length of time a laser pulse lasts, usually in microseconds, nanoseconds, or milliseconds

Pulse repetition

The rate at which a laser fires pulses, usually in pulses per second or Hertz

Pulsed dye

Laser that produces light from an organic dye solution

Purpura

A purplish or blue/black discoloration in the skin after laser treatment, a.k.a. bruise

Q-switching

The use of a pockel cell to generate very high peak power for a very short period of time (pulse width), usually in the nanosecond range

Reflection

The act of light bouncing off of a surface after striking it

Resonator

AKA laser head or laser cavity, or laser tube. The place where the lasing medium is housed and the laser energy is produced

Rhytides

Wrinkles, usually referring to the face, and the result of cumulative photodamage

Rosacea

Dilation of capillaries in the cheeks, nose, forehead, and chin

Scars

Fibrous tissue formed during the healing of a wound

Scattering

Process in which a light beam is split apart in many different directions after striking a object or tissue

Sclerotherapy

The injection of a chemical into a vein to obliterate the vessel

Seborrheic Keratosis

A benign pigmented lesion which is raised, tan, brown or black colored, usually on the face, back and chest of elderly people and have a greasy wart-like appearance

Selective Photothermolysis

Theory on which lasers are designed which states that one chooses a laser wavelength that a target absorbs strongly, while surrounding structure do not, and having an expose time less than the thermal relaxation time of the target.

Selectivity

Being absorbed by a particular target, while not affecting surrounding structures

Spider Hemangioma

A dilated arteriole of the skin with radiating capillary branches (Arterial spider)

Stimulated emission

Process by which a moilecule emits two photons of light after absorbing one

Target

Tissue or substance a laser beam is directed at

Telangiectasia

Dilation of a group of capillaries, also called spider veins

Thermal injury

Damage to tissue from a heart source or photo-thermal reaction

Topical anesthesiay

Anesthetic applied to the surface of the skin, usually a cream, liquid, or gel

Transient/Transitory

Temporary

Transmission

The passage of energy through a medium

TRT

Thermal Relaxation Time - the time a target takes to release 1/2 the heat it had gained after being heated

Ulceration

A depressed or eroded area in the skin

Warts

A small horny outgrowth on the skin, usually or viral origin, also called verucca

Wavelength

The distance between two consecutive peaks on a wave of light. Usually measured on micrometers or nanometers. Also determines the color of the light

Wheal

Round or ridge-like transitory swelling on skin